The strong growth in demand for portable consumer electronics is driving the need for high-capacity storage devices. Non-volatile semiconductor memory devices, such as flash memory storage cards, are becoming widely used to meet the ever-growing demands on digital information storage and exchange. Their portability, versatility and rugged design, along with their high reliability and large capacity, have made such memory devices ideal for use in a wide variety of electronic devices, including for example digital cameras, digital music players, video game consoles, PDAs and cellular telephones.
While many varied packaging configurations are known, flash memory storage cards may in general be fabricated as system-in-a-package (SiP) or multichip modules (MCM), where a plurality of die are mounted and interconnected on a small footprint substrate. The substrate may in general include a rigid, dielectric base having a conductive layer etched on one or both sides. Electrical connections are formed between the die and the conductive layer(s), and the conductive layer(s) provide an electric lead structure for connection of the die to a host device. Once electrical connections between the die and substrate are made, the assembly is then typically encased in a molding compound which provides a protective package.
Cross-sectional side and top views of a conventional semiconductor package 20 are shown in FIGS. 1 and 2. Typical packages include a plurality of semiconductor die, such as flash memory die 22 and a controller die 24, supported on a substrate 26. Substrate 26 includes vias, electrical traces and contact pads for transferring signals between the semiconductor die 22, 24 and a host device in which the package is located. Die bond pads 28 may be formed on a surface of the semiconductor die 22, 24 to electrically couple the semiconductor die to the substrate by affixing wire bonds 32 between respective die bond pads and contact pads. Once all electrical connections are made, the die and wire bonds may be encapsulated in a molding compound 34 to seal the package and protect the die and wire bonds.
With the ever-present drive to provide more storage capacity in a smaller package, there is a need to rethink the use of substrates and how the semiconductor die are arranged within the semiconductor package.